June ii, 1917 
Eupatorium ageratoides; Cause of Trembles 
399 
bodies of affected sheep and horses, and in the soil in regions where 
milksickness prevails. Taken as a whole, however, the experiments were 
far from decisive in showing that B . lactimorbi is the etiological factor 
in the production of trembles, or milksickness. 
METHODS OF experimentation 
Since E. ageratoides, commonly called “ white snakeroot,” does not 
grow in the vicinity of Raleigh, N. C., where the experiments were con¬ 
ducted, it was arranged to secure daily shipments of the green weed from 
Shooting Creek, N. C., where E. ageratoides , locally known as“ rich weed,” 
grows luxuriantly, especially in shady situations. Since this place is 
about 300 miles distant from Raleigh, the weed used had been cut about 
48 hours prior to its arrival at Raleigh. The weed was fed twice daily 
to sheep kept singly in small pens in a sheep bam. A maintenance 
ration of some dry concentrate was given in addition to this green food. 
The animals used were selected from the experimental flock of grade 
ewes, all of which were in a healthy condition and, with the exception 
of those used in the experiments, remained so. The flock number of each 
individual was retained and is used subsequently in reporting the experi¬ 
ments with the several animals. No case of trembles had ever appeared 
in this or any other of the Station flocks prior to or during the course 
of these experiments. 
Each animal was weighed when it was placed on the experiment and 
at time of death. Beginning with experiment 3, in addition to the 
initial weighings subsequent weighings were made at 3-day intervals 
until the experiment was concluded or until death resulted. At first the 
grain and weed were fed separately; but, since the animals either avoided 
eating any of the weed or ate onjy sparingly of it, the weed was passed 
through an ensilage cutter and then mixed with grain before being fed. 
A daily account was kept of all of the food which was refused by each 
animal, and these data were employed in approximating the total amount 
consumed during the course of the experiment. The quantity of E. 
ageratoides eaten by each animal could only be approximated, since the 
weed and grain refused were mixed and since some loss of weight was 
due to desiccation. Post-mortem examinations were made of ewes 10, 
11, 14, 27, 161, and 169. With the exception of ewe 169, the post¬ 
mortem examination showed no evidence that death resulted from any 
other cause than the feeding of E. ageratoides . Post-mortem examina¬ 
tions were not made of the other animals, because the external symptoms 
were clearly those which characterize trembles. 
SYMPTOMS OF TREMBLES 
Since the possibility exists that trembles in animals may develop from 
causes other than the feeding of E . ageratoides and that the symptoms 
may differ somewhat from those resulting from the ingestion of this 
